<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="bootstrap-5.3.0-dist/css/bootstrap.min.css">
</head>
<body>
  <p class="h1">一级标题</p>
  <p class="h2">二级标题</p>
  <span class="h3">三级标题</span>
  <a href="#" class="h4">四级标题</a>
  <span class="h5">五级标题</span>
  <div class="h6">六级标题</div>
</body>
</html>